It is known that in shops for vehicles there is the necessity of having access to the lower part of the vehicles to repair those which have been involved in accidents or which have a malfunction.
For the purpose of allowing the operator or operators to have access to the lower part of the vehicle there are used the so called "banchi di tiro" which are roller stands constituted essentially by a base frame of a rectangular shape which has some openings for the passage of templates on which the vehicle is placed and the vehicle is moved in a vertical direction by lifting means which are constituted in many instances by pantograph trolley mechanisms.
The roller stands have a structure which is heavy and complex and are provided with devices for blocking the vehicle which allow the drawing operations in the body shop, operations which impart substantial turnover stresses both on the vehicle and on the roller stands. For this reason the use of the known roller stands constitutes substantial cost, long and complex work procedures which frequently are not justifiable in small operations of repair and servicing.
In the body shops there are also in use simple power lifts which have a bearing plane with a mechanism involving pantograph trolleys which do not have almost totally the blocking devices for the vehicles because the stability of the vehicle is insured only for the operations in which substantial stresses or substantial drawing are not involved.
The problems described hereinabove are further aggravated in the case in which it is necessary to carry out repair operations or layout operations of the body shop or on the frame of heavy autovehicles. In fact, in order to work effectively and with safety on heavy autovehicles a particular stability of the structure of the power lift is required. However the known power lifts presently available for heavy materials require too much space and the operation of lifting the vehicle becomes difficult particularly in the first part of commencing the lifting operation.
In fact the known power lifts are provided with actuators which in the state in which it is necessary to form a pack act for lifting the vehicle in the first phases according to directions which are almost horizontal requiring therefore for lifting the vehicle very high pressures of the fluid and these pressures are incompatible with the common sources of pressure which are available to the body shops.
For the purpose of overcoming the problems related to the stresses and the first phases of lifting the vehicles various devices have been conceived which are constituted by stirrups capable of carrying out the initial push so as to improve the efficacy of the push of the actuators on the lifting levers.
Normally these devices used for improving the ratio between the lifting stroke and the pushing stroke are positioned corresponding to the articulation of the lifting levers but in the known configurations they have been shown to be effective only in the case of light vehicles because if they are used with heavy vehicles they are totally inadequate to limit the pressures necessary for the lifting of the vehicles at least in the initial phase.